socket.io room join socket.id express api On Nodejs 5.1.0 + socket.io 1.3.7

• How to use socket.io in express routes?
• Proper way to return JSON using node or Express
• 4.x API - express()

/**
 * socket.id count 4 roomid 
 * nodejs. 5.1.0
 * express 4.13.3
 * socket.io 1.3.7
 */
app.get( '/api/v1/status/join/:roomid', function(req, res){
	var roomJoined = 0;
	try{
		roomJoined = _.pairs(io.sockets.adapter.rooms[req.params.roomid]).length;
	}catch(e){
		console.error('/api/v1/status/join/', __line, e );
	}
	
	console.log('/api/v1/status/join/', __line, req.params );
	
	res.setHeader('Content-Type', 'application/json');
	res.send( 200, JSON.stringify({result:true, type:'join', cnt: roomJoined }) );
	res.end();
});